Vulcanized rubber can be devulcanized and the resultant products re-used in new goods. The resultant products of the devulcanization process may depend on the technique used to devulcanize the vulcanized rubber. For example, U.S. Pat. No. 7,166,658, which is hereby incorporated by reference in its entirety, teaches processing used tires to obtain 100% devulcanized rubber. The devulcanized rubber may then be further processed to separate the polymer from carbon black, possibly using the process described in U.S. Pat. No. 8,415,402, which is hereby incorporated by reference in its entirety. The 100% devulcanization process can result in polymer scission, which may alter the characteristics of the devulcanized rubber and may be undesirable in certain applications.
U.S. patent application Ser. No. 14/090,723, and corresponding International patent application PCT/CA20131050903, titled Vulcanized Rubber Conversion describes a process for the conversion of vulcanized rubber material, such as used tires or other scrap materials, to produce a product that is suitable for use as a component in the production of other rubber materials. When the vulcanized rubber is converted according to a process described by U.S. patent application Ser. No. 14/090,723 the devulcanized rubber cannot be separated into polymer and carbon black. However, the devulcanized rubber has characteristics suitable for inclusion in new rubber formulations as a substitute for virgin rubber. The vulcanized rubber conversion may be carried out in water at elevated temperatures and pressures. The devulcanized rubber after processing may contain 15-40% water by weight, which may be undesirably high for certain applications. The amount of water in a rubber sample may be estimated by drying the sample at 110° C. until its weight is constant for a sufficient period of time, such as 24 hours. The weight lost is assumed to be the weight of the water present in the sample.
Various techniques for removing the water from the devulcanized rubber exist, including for example, air drying at elevated temperature, or mechanically drying by squeezing between rollers or screws. However, drying at elevated temperatures may have undesirable effects on the devulcanized rubber, including making the surface hard which makes it more difficult to mix with and recombine into new products, while squeezing may not remove enough of the water from the devulcanized rubber.
An additional alternative dewatering technique for removing water from devulcanized rubber is desirable.